Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 38,986
  • Total confirmed cases: 5,907
  • Deaths from Confirmed Cases: 1,079
  • Case Fatality Ratio: 20%
  • Number of Health Care Workers: 229

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 10

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 2,964 suspected cases were reported from 1 in Niger, Akwa Ibom, Jigawa to 955 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 33% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 23% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 10, 88% of LF cases are from Ondo (31%), Bauchi (25%), Edo (17%), and Taraba (15%) States.

  • Total confirmed cases: 563

  • Deaths from Confirmed Cases: 103

  • Case Fatality Ratio: 18%

  • Number of Health Care Workers: 17

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 10 2025, cumulatively 563 cases and 103 deaths (CFR=18%) across 14 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 33% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 23% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 34 States had reported at least one suspected case versus 31 States in 2025 to date.
    • 27 States had reported at least one confirmed case versus 14 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 10


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 2 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Edo.

  • As of epi week 10 of 2025, there has been 17 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 10)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 790 175 21 12%
2024 895 170 12 7%
2023 925 244 26 11%
2022 540 187 33 18%
2021 200 45 12 27%
2020 350 279 38 14%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 175 confirmed cases including 21 deaths (CFR 12%).
  • Compared to same period 2024, this represents:
    • 12% decrease in the number of suspected cases.
    • 3% increase in the number of confirmed cases.
    • 70% increase in CFR.




  • In 2024 as of week 10:
    • 895 in the number of suspected cases.
    • 170 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 10:
    • 925 in the number of suspected cases.
    • 244 in the number of confirmed cases.
    • 26 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 10:
    • 540 in the number of suspected cases.
    • 187 in the number of confirmed cases.
    • 33 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 10:
    • 200 in the number of suspected cases.
    • 45 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 27% average CFR.




  • In 2020 as of week 10:
    • 350 in the number of suspected cases.
    • 279 in the number of confirmed cases.
    • 38 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 577 139 11 8%
2024 473 109 26 24%
2023 520 71 10 14%
2022 541 95 10 11%
2021 31 6 2 33%
2020 175 35 11 31%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 139 confirmed cases including 11 deaths (CFR 8%).
  • Compared to same period 2024, this represents:
    • 22% increase in the number of suspected cases.
    • 28% increase in the number of confirmed cases.
    • 67% decrease in CFR.




  • In 2024 as of week 10:
    • 473 in the number of suspected cases.
    • 109 in the number of confirmed cases.
    • 26 in the number of deaths.
    • 24% average CFR.




  • In 2023 as of week 10:
    • 520 in the number of suspected cases.
    • 71 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 14% average CFR.




  • In 2022 as of week 10:
    • 541 in the number of suspected cases.
    • 95 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 11% average CFR.




  • In 2021 as of week 10:
    • 31 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 33% average CFR.




  • In 2020 as of week 10:
    • 175 in the number of suspected cases.
    • 35 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 31% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 955 98 15 15%
2024 1029 168 23 14%
2023 1208 219 28 13%
2022 922 154 20 13%
2021 730 87 11 13%
2020 761 288 31 11%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 98 confirmed cases including 15 deaths (CFR 15%).
  • Compared to same period 2024, this represents:
    • 7% decrease in the number of suspected cases.
    • 42% decrease in the number of confirmed cases.
    • 12% increase in CFR.




  • In 2024 as of week 10:
    • 1029 in the number of suspected cases.
    • 168 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 14% average CFR.




  • In 2023 as of week 10:
    • 1208 in the number of suspected cases.
    • 219 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 13% average CFR.




  • In 2022 as of week 10:
    • 922 in the number of suspected cases.
    • 154 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 13% average CFR.




  • In 2021 as of week 10:
    • 730 in the number of suspected cases.
    • 87 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 13% average CFR.




  • In 2020 as of week 10:
    • 761 in the number of suspected cases.
    • 288 in the number of confirmed cases.
    • 31 in the number of deaths.
    • 11% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 203 84 26 31%
2024 149 83 18 22%
2023 189 67 24 36%
2022 52 23 10 43%
2021 46 18 11 61%
2020 64 47 17 36%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 84 confirmed cases including 26 deaths (CFR 31%).
  • Compared to same period 2024, this represents:
    • 36% increase in the number of suspected cases.
    • 1% increase in the number of confirmed cases.
    • 43% increase in CFR.




  • In 2024 as of week 10:
    • 149 in the number of suspected cases.
    • 83 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 22% average CFR.




  • In 2023 as of week 10:
    • 189 in the number of suspected cases.
    • 67 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 36% average CFR.




  • In 2022 as of week 10:
    • 52 in the number of suspected cases.
    • 23 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 43% average CFR.




  • In 2021 as of week 10:
    • 46 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 10:
    • 64 in the number of suspected cases.
    • 47 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 36% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 82 17 8 47%
2024 177 42 23 55%
2023 130 46 24 52%
2022 158 33 13 39%
2021 66 12 4 33%
2020 113 59 14 24%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 17 confirmed cases including 8 deaths (CFR 47%).
  • Compared to same period 2024, this represents:
    • 54% decrease in the number of suspected cases.
    • 60% decrease in the number of confirmed cases.
    • 14% decrease in CFR.




  • In 2024 as of week 10:
    • 177 in the number of suspected cases.
    • 42 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 55% average CFR.




  • In 2023 as of week 10:
    • 130 in the number of suspected cases.
    • 46 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 52% average CFR.




  • In 2022 as of week 10:
    • 158 in the number of suspected cases.
    • 33 in the number of confirmed cases.
    • 13 in the number of deaths.
    • 39% average CFR.




  • In 2021 as of week 10:
    • 66 in the number of suspected cases.
    • 12 in the number of confirmed cases.
    • 4 in the number of deaths.
    • 33% average CFR.




  • In 2020 as of week 10:
    • 113 in the number of suspected cases.
    • 59 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 24% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 62 15 4 27%
2024 89 27 1 4%
2023 28 10 1 10%
2022 60 27 6 22%
2021 4 0 0 –
2020 60 29 8 28%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 30% decrease in the number of suspected cases.
    • 44% decrease in the number of confirmed cases.
    • 620% increase in CFR.




  • In 2024 as of week 10:
    • 89 in the number of suspected cases.
    • 27 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 4% average CFR.




  • In 2023 as of week 10:
    • 28 in the number of suspected cases.
    • 10 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 10% average CFR.




  • In 2022 as of week 10:
    • 60 in the number of suspected cases.
    • 27 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 22% average CFR.




  • In 2021 as of week 10:
    • 4 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 10:
    • 60 in the number of suspected cases.
    • 29 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 28% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 48 11 6 55%
2024 24 3 1 33%
2023 24 6 0 0%
2022 92 15 6 40%
2021 2 0 0 –
2020 14 5 1 20%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 11 confirmed cases including 6 deaths (CFR 55%).
  • Compared to same period 2024, this represents:
    • 100% increase in the number of suspected cases.
    • 267% increase in the number of confirmed cases.
    • 64% increase in CFR.




  • In 2024 as of week 10:
    • 24 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 10:
    • 24 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 10:
    • 92 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2021 as of week 10:
    • 2 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 10:
    • 14 in the number of suspected cases.
    • 5 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 20% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 10:
Years Suspected cases Confirmed cases Deaths CFR
2025 27 5 3 60%
2024 921 59 9 15%
2023 82 32 3 9%
2022 181 30 8 27%
2021 9 2 0 0%
2020 20 7 2 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 5 confirmed cases including 3 deaths (CFR 60%).
  • Compared to same period 2024, this represents:
    • 97% decrease in the number of suspected cases.
    • 92% decrease in the number of confirmed cases.
    • 293% increase in CFR.




  • In 2024 as of week 10:
    • 921 in the number of suspected cases.
    • 59 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 15% average CFR.




  • In 2023 as of week 10:
    • 82 in the number of suspected cases.
    • 32 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 9% average CFR.




  • In 2022 as of week 10:
    • 181 in the number of suspected cases.
    • 30 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 27% average CFR.




  • In 2021 as of week 10:
    • 9 in the number of suspected cases.
    • 2 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 10:
    • 20 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon